Refrigeration device for container

Abstract

A container refrigeration device aims to prevent low temperature damage to freight in a container. The container refrigeration device includes: a temperature controlling section ( 101 ) configured to perform, in a switchable manner, first temperature control under which a temperature inside the container (C) is controlled based on a blown air temperature (Tss) and second temperature control under which the temperature inside the container (C) is controlled based on a suction air temperature (Trs) during dehumidification operation; and a control switching section ( 103 ) configured to switch the first temperature control to the second temperature control when the blown air temperature (Tss) is higher than the suction air temperature (Trs) during the dehumidification operation in which part of a refrigerant discharged from a compressor ( 30 ) is allowed to flow into a reheat heat exchanger ( 83 ).

The invention claimed is: 
     
       1. A container refrigeration device comprising:
 a refrigerant circuit including a compressor, a condenser, an expansion valve, and an evaporator sequentially connected together; and 
 a reheat heat exchanger configured to allow part of a refrigerant discharged from the compressor to directly flow into the reheat heat exchanger, the device being configured to perform dehumidification operation during which air sucked from an inside of a container and subjected to cooling dehumidification in the evaporator exchanges heat with the refrigerant flowing through the reheat heat exchanger, wherein 
 the device further includes
 a suction air temperature detector configured to detect a suction air temperature which is a temperature of air being sucked into the evaporator from the inside of the container, 
 a blown air temperature detector configured to detect a blown air temperature which is a temperature of air having passed through the reheat heat exchanger and being blown into the inside of the container, 
 a temperature controlling section configured to perform, during the dehumidification operation, a first temperature control under which a temperature inside the container is controlled in such a manner that at least one of the compressor and the expansion valve is controlled to cause the blown air temperature to approach a predetermined first target temperature, and a second temperature control under which the temperature inside the container is controlled in such a manner that at least one of the compressor and the expansion valve is controlled to cause the suction air temperature to approach a predetermined second target temperature, in a switchable manner, and 
 a control switching section configured to switch from the first temperature control to the second temperature control when the blown air temperature is higher than the suction air temperature during the dehumidification operation during which the part of the refrigerant discharged from the compressor is allowed to flow into the reheat heat exchanger. 
 
 
     
     
       2. The container refrigeration device of  claim 1 , wherein
 the device further includes a temperature setting section ( 104 ) configured to set the second target temperature to a value obtained by adding a correction value to the first target temperature. 
 
     
     
       3. The container refrigeration device of  claim 2 , wherein
 the temperature setting section is configured to set the correction value to a predetermined fixed value. 
 
     
     
       4. The container refrigeration device of  claim 2 , further comprising:
 an outside air temperature detector configured to detect an outside air temperature which is a temperature of air outside the container, wherein 
 the temperature setting section is configured to calculate the correction value based on the outside air temperature and the first target temperature. 
 
     
     
       5. The container refrigeration device of  claim 2 , wherein
 the temperature setting section is configured to calculate the correction value based on a difference between the blown air temperature detected before starting of the dehumidification operation during which the refrigerant discharged from the compressor is allowed to flow into the reheat heat exchanger and the suction air temperature detected after the starting of the dehumidification operation.